Hydraulic power unit



June 3, 1958 J. THORPE 2,837,062

HYDRAULIC POWER UNIT Filed March 28, 1957 2 Sheets-Sheet l INVENTORJZLse Z/Z'kar e ATTORNEY June 3, 1958 J. THORPE 2,837,062

HYDRAULIC POWER UNIT Filed March 28, 1957 2 Sheets-Sheet 2 7/ 7/ i 7;sum/ T INVENTOR /i JZse faz we Ham/ m, ATTORNEY United States PatentOfitice Patented June 3, 1955 HYDRAULIC POWER UNIT Joseph Thorpe, EggHarbor City, N. J.

Application March 28, 1957, Serial No. 649,175

7 Claims. (Cl. 121-63) My invention relates to an hydraulic power unitfor converting a high speed power source into a low speed power supplyof greater torque.

In accordance with the invention, a high speed internal combustionengine, if the power unit is to be used on a boat or on a mobile unit,or an electric motor, if it is to be used where there is electriccurrent, is employed to drive a pump which supplies an hydraulic fluidunder pressure.

The hydraulic fluid is sequentially supplied to a plurality of pivotallymounted cylinders to reciprocate double-acting pistons operating withinthe cylinders and thereby to rotate, by means of connecting rods and acrank, a drive shaft at low speed with great torque.

An object of the invention is to provide a power unit that is especiallyadapted for use in boats where a large screw or propeller is used to bedriven at a low rate, say 100 to 150 R. P. M.s, thus to give greatdriving torque to the screw, rather than attempting to drive a smallerscrew at a high rate of speed.

Another object of the invention is to produce a power unit that willhave the drive Shaft turn with great torque at a minimum number of R. P.M.s, and at the same time not require any reduction gears.

An hydraulic pump driven by an internal combustion engine may be mountedin any part of the boat with a pipe line running to the power unit atthe stern, or the engine and driven unit may be closely associated, ifso desired.

Another object of the invention is to provide a power unit that may beused, for instance, on a boat, a bulldozer, a crane, or in a shop, wherea slow rate of R. P. M.s is essential, but with greater torque than thatproduced where there is a high rate of R. P. M.s of the crank shaft.

With these and other objects in view, the invention consists in certainnew and novel construction and combination of parts, as will behereinafter more fully pointed out and described in the accompanyingdrawings, in which:

Fig. 1 is a front elevation of an illustrative apparatus constructed inaccordance with the invention,

Fig. 2 is a top plan view of the apparatus shown in Fig. 1,

Fig. 3 is a cross-section taken on line 3-3 of Fig. 2, and showing themounting of the cylinders and the operation of the cam-carrying driveshaft,

Fig. 4 is a partial horizontal cross-section through the inlet valveblock, showing the valves and the manner in which these valves areactuated in time relation by means of the cams carried by the driveshaft,

Fig. 5 is a cross-section taken on line 5-5 of Fig. 2 and showing themovement of hydraulic fluid through the power unit, and

Fig. 6 illustrates a refinement of the invention which permits the driveshaft to be selectively powered in either direction and which alsopermits the apparatus to idle,

e. g., to remain at rest despite the continued operation of the highspeed power source.

Referring more particularly to the drawings, and with particularreference to Figs. 1 and 2, the numeral 10 designates an electric motorwhich constitutes the high speed power source. The motor 10 drives apump 11 by means of the pulleys 12 and 13 and the belt 14.

The power unit illustratively shown in the drawings includes an inletblock 15, an outlet block 16, a drive shaft 17, hydraulically operateddouble-acting cylinders 18 and 19, and a sump 20. These various itemsare supported by a pair of upright plates 21 and 22 between which thecylinders 18 and 19 are mounted for pivotal movement.

More particularly, the motor 10, the pump 11, and the sump 20 can besecured to any suitable supporting surface by means not shown; and theupright plates 21 and 22 are also secured to the supporting surface toposition the plates 21 and 22 in substantially parallel spaced.

apart planes.

The plate 21 carries the inlet block 15 and the outlet block 16, whichmay be welded or bolted or otherwise fixedly secured in place. Theblocks 15 and 16 each provides a plurality of juxtaposed valves. Thevalves of the inlet block 15 are designated 23, 24, 25 and 26; and thecorresponding juxtaposed valves of the outlet block are designated 23',24, 25 and 26. The drive shaft 17 is supported in hearings in the plates21 and 22 and projects from between the plates 21 and 22 to extendbetween the blocks 15 and 16 intermediate the valves 23, 23', etc,

The portion of the draft shaft 17 which lies between the plates 21 and22 is V-shaped to provide a crank 27. The portion of the drive shaft 17which extends between the blocks 15 and 16 carries a plurality of valveactuating cams, one for each of the juxtaposed pairs of valves, 23, 23,etc. The valve actuating cams are designated 28, 29, 30 and 31, andthese bear against followers 32,- 33, 34 and 35 in the blocks 15, andfollowers 32, 33', 34' and 35 in the block 16.

As will be evident, the earns 28, 29, 30 and 31 operate the followers inopposite directions so that when one of the valves 23-26 is open, thejuxtaposed valve of the group of valves 2326' is closed, and vice versa.

The cylinders 18 and 19 are each 'mounted for pivotal movement in theplane of the plates 21 and 22 by means of shafts 36, which are suitablysupported in hearings in the plates 21 and 22. These cylinders 18 and 19are double-acting so that both strokes of the piston in each pistoncycle is positively powered.

Each cylinder is provided with a piston 37, which is slidingly mountedfor reciprocating movement along the longitudinal axis of the cylinder.The pistons 37 are fixedly secured to connecting rods 38 which arepivotally secured to the crank 27 of the drive shaft 17. The cylinders18 and 19 are offset from each other along the length of the shaft 17 sothat the connecting rods 38 can simultaneously drive the crank 27 As thecrank 27 rotates, the lower end or" connecting rods 38 rotate with it;and the cylinders 13 and 19 are pivoted so that the lower end of thecylinders are sealed, permitting the pistons to be double-acting.

The movement of the cylinder 18 is illustrated in Fig. 1, where thefurthest upwardly tilted position of the cylinder 18 is shown in fulllines, and the furthest downwardly tilted position is shown in dottedline.

In Fig. 3, it can be seen that the connecting rod 38 emerges from thelower extremity of the cylinder 18 through a tightly fitted orifice 39,which is packed to provide a fluid-tight seal between the orifice 39 andthe connecting rod 38.

Referring again to Figs. 1 and 2, and with particular reference to Fig.2, the path of hydraulic fluid from the 3 sump 20 through the cylinders13 and 19 and then back again to the sump 20 can be seen clearly.

The hydraulic fluid, e. g., oil, is pumped from the sump 20 through theline 40 to the pump 11, and is forced from this pump 11 through line 41into the inlet valve block 15. A common inlet may be used for all of theinlet valves 23, 24, 25 and 26; or, the line 41 may be provided withbranches, one for each of the inlet valves.

In the form illustrated, the hydraulic fluid is supplied to all of theinlet valves via the common line 41, the bores 42, and the recessedchannels 43. (-See Figs. 4 and 5.)

As can be seen in Fig. 2, line 44 interconnects valve 23 with the upperend of cylinder 18; and line 45 interconnects valve 24 with the lowerend of cylinder 18. Lines 46 and 47 interconnect the valves 25 and 26with the lower and upper ends respectively of the cylinder 19. Each ofthe lines 44, 45, 46 and 47 is provided with a T connection 48 to whichis connected a drain line .49 which leads to the juxtaposed outlet valvein the block 16.

The operation of the inlet and outlet valves is timed so that when theinlet valve is open, the corresponding juxtaposed outlet valve is closedand vice versa. Since the inlet and outlet valves are connected togetherthrough the T connection 48 and the drain line 49, when the inlet valveis open fluid can move through the inlet valve to the cylinder, and thisfluid cannot go directly to the sump because the outlet valve is closed.

When the outlet valve is open, the inlet valve is closed. As a result,when fluid is discharged from the cylinder, the inlet valve is closedand the discharged fluid is directed to the open outlet valve through Tconnection 48 and drain line 49 and thence to the sump 20 for furtheruse. To avoid splashing of oil, downspouts 50 are provided to directfluid discharged from the outlet block 16 to the sump 20 beneath thelevel of the hydraulic fluid therein.

The positioning of the earns 28, 29, 30 and 31 is clearly shown in thedrawings where each cam is mounted for valve actuation 90 apart. Thesequential action of the valves 23, 24, 25 and 26 of inlet block 15 isas follows: first, valve 23 opens; second, valve 25 opens; third, valve24 opens; and fourth, valve 26 opens. As will be obvious, each of valves23, 24, 25 and 26 is forced to close 180 after opening. The degreesreferred to are degrees of rotation of the drive shaft 17. The action ofthe juxtaposed valves 23', 24', 25 and 26 is exactly the opposite of thevalves 23, 24,, 25 and 26, as has been previously explained, and as isbest seen in Fig. 5. The timing of the valves 23, 24, 25 and 26 is bestseen in Fig. 4.

The structure of valves 23, 24, 2S and 26 is clearly shown in Figs. 4and 5, Where it will be seen that the followers 32, etc., are slidinglymounted for longitudinal reciprocation in yokes 51 which are secured tothe blocks 15 and 16. The valve in each block is bored to provide alarge diameter valve element receiving cylindrical chamber 52 withinwhich the valve element 53 is mounted.

The valve element 53 is trapped within the chamber 52 by a cap 54threaded to the blocks 15 and 16, as shown. Within the cap 54 springs 55bias elements 53 towards the followers and the cams 28, etc. Eachelement 53 is provided with a small diameter projection 56 and ashoulder 57 and the chamber 52 leads to a small diameter base 58 whichprovides a seat 59 against which shoulder 57 bears to prevent fluid fromreaching the lines 44, etc., to thereby close the valve. As will beunderstood, in the absence of cam actuation, springs 55 bias elements 52into closing position, and the action of the cams 23, etc., overcomesthe springs 55 to open the valves.

As will now be evident, the operation of the power unit is as follows:first, valve 23 opens (23' closed) and fluid enters the top of cylinder18 to force piston 37 down; second, valve 25 opens (25' closed) andfluid enters the bottom of cylinder 19 to force its piston up; third,valve 24 opens (24 closed) and fluid enters the bottom of cylinder 18,forcing the piston of cylinder 18 up and ejecting fluid through lines 44and 49 to the now open valve 23 (23 closed); fourth, valve 26 opens (26'closed) and fluid enters the top of cylinder 19 forcing the piston ofcylinder 19 down and ejecting fluid through lines 46 and 49 to the nowopen valve 25 (25 closed) and so on.

In the preferred embodiment illustrated, the cylinders 18 and 19 aremounted at an angle of about 90 with rcspect to one another in V-fashionwith respect to the crank 27.

The outlet valves 23 etc., are similar to the inlet valves. As can beseen at the right hand portion of Fig. 5, the downspouts 50 communicatewith a chamber 60 positioned in advance of the shoulder 59 so that thevalve is open whenever the cams 23, etc., overcome the pressure ofsprings 55 in the outlet valves.

As an indication of preferred structural detail, the followers 35, 35',etc., are provided with arcuate heads 61 and also with threadedadjustable members 62 at the ends of the followers which engage theprojections 56 so that the valve action can be precisely adjusted.

The modification of Fig. 6 interposes a reversing valve broadlydesignated in the various lines 44, 45, 46, and 47 in the constructionpreviously shown. Thus, instead of lines 44 and 45 leading directly tothe cylinder 18, these lines, in the form shown in Fig. 6, lead to thevalve 70, and lines 44' and 45 lead from the valve 79 to the cylinder18.

As will be evident, adjustment of valve 70 can function to switch theconnections so that line 44 will supply line 45' and hence the lower endof cylinder 18. This serves to reverse the timing and the direction ofrotation of drive shaft 17.

Specifically, reversing valve 70 is constituted by a cylinder 71 havinga rod 72 fitted therewithin. The rod 72 is formed with circumferentialrecesses 73. The inlet lines 44, 45, etc., are branched as indicated at74, and the lines 44', 45, etc., are also branched as indicated at 75.

The branches span a distance which is different from the distancebetween adjacent recesses 73 on the rod 72, so that only one end of thebranches 74 and 75 is interconnected at any position of rod 72.

In the position shown in Fig. 6, the shaft 17 will rotate in the samedirection as with the construction shown in Figs. 1-5. However, if rod72 is moved to the right a distance of half the span between adjacentrecesses 72, then the direction of rotation is reversed.

Rod 72 can also be moved to an intermediate position at which therecesses 72 do not link together any of the branches 74 and 75. Whenthis happens the pump 11 and hence the motor 10 may be unduly burdenedby the pumping of fluid into a blind passageway. To avoid this, thisintermediate position is utilized as shown at the right hand portion ofFig. 6 to connect a line 76 leading directly to the sump 20.

It will be understood that the invention has been illustrativelydescribed and many structural variations can be made without departingfrom the invention, the scope of which is defined in the claims whichfollow.

I claim:

1. A power unit comprising a plurality of pivotally mounted cylinders,double-acting pistons mounted for longitudinal reciprocation within saidcylinders, a drive shaft including a crank portion, connecting rodsfixed to said pistons and connected with said crank portion, saidconnecting rods extending through the closed lower end of said cylindersand being slideably mounted with respect to said cylinders influid-tight manner, means for supplying fluid under pressure, an inletvalve block communicating with said fluid supply and comprising aplurality of valves, one for each end of said cylinders, an outlet valveblock comprising a plurality of valves, one for each end of saidcylinders, conduit means separately interconnecting each of said valvesof said inlet valve block with one of the upper and lower ends of saidcylinders, conduit means separately interconnecting each of said valvesof said outlet valve block with one of the upper and lower ends of saidcylinders, means to actuate said valves of said inlet valve block intimed sequential relation, and means to oppositely actuate the valve ofsaid outlet valve block which is connected with the same end of the samecylinder.

2. A power unit as recited in claim 1 in which said inlet valve blockand said outlet valve block are laterally juxtaposed with respect toeach other and said drive shaft extends between said valve blocks andprovides cams for actuating the valves of both of said valve blocks.

3. A power unit as recited in claim 2 in which said oppositely actuatedvalves are laterally juxtaposed with respect to each other and areactuated simultaneously by the same cam on said drive shaft.

4. A power unit as recited in claim 3 in which said valves arespring-biased toward the cams on said drive shaft.

5. A powerunit as recited in claim 1 in which said first-named conduitmeans includes a T connection and said second-named conduit means issecured to said T connection.

6. A power unit as recited in claim 1 in which said first-named conduitmeans is constituted by first and sec- 0nd conduits having a pairof'branches communicating with a valve cylinder, said first conduitscommunicating with said inlet valves and said second conduitscommunicating with said pivotally mounted cylinders, a valve rod movablymounted within said valve cylinder, said valve rod having means forintercommunicating one branch of said first conduits with one branch ofsaid second conduits, said branches being positioned so that in oneposition of said rod said conduits are connected to operate said driveshaft in one direction, and in another position of said rod saidconduits are connected to operate said drive shaft in the oppositedirection.

7. A power unit as recited in claim 6 in which said valve rod isprovided with longitudinally spaced circumferential recesses forintercommunicating one branch of said first conduits with one branch ofsaid second conduits, and said valve rod is mounted within said cylinderfor sliding movement along the length thereof.

References Cited in the file of this patent UNITED STATES PATENTS919,207 Norton Apr. 20, 1909 1,229,076 Hayes June 5, 1917 1,328,160 LawnJan. 13, 1920 1,576,830 Jordan et al Mar. 16, 1926 2,604,078 ChelminskiJuly 27, 1952 2,687,118 Bennett Aug. 24, 1954

